(CNN) - Australian fisheries authorities have killed six sharks in the area of the Whitsunday Islands where two people were critically injured in shark attacks last week.
A 46-year-old woman and a 12 year-old girl were bitten in separate incidents within 24 hours of each other.
The attacks, on Wednesday and Thursday, occurred in Cid Harbour, a picturesque bay surrounded by beaches in a popular tourist area on the north coast of Queensland.
The Queensland Department of Agriculture and Fisheries said Monday that six sharks -- including a 3.7-meter (12-foot) tiger shark -- had been caught since three drum lines were temporarily deployed on Friday. Drum lines are a system of buoys "designed to remove larger, dangerous sharks from an area," a Fisheries Queensland spokesman said.
"As per the Fisheries Queensland protocol, the sharks were humanely euthanized, measured and taken out to sea for disposal," a Fisheries Queensland spokesman said in a statement.
"The message is these waters are not safe for swimming. During this holiday period, we urge people to exercise caution, stay out of the water and not throw foodscraps overboard from boats."
A fisheries vessel has also been patrolling the harbor, advising people not to swim in the area.
The Fisheries department's actions have been criticized, with Humane Society Australia posting its objection to Twitter on Sunday.
"HSI acknowledges the need for bather protection, however culling sharks is not the solution. Personal shark deterrents, aerial surveillance, improved alert systems & education are more effective measures to reduce the incidence of shark-human interactions," the group said.
Excluding the two most recent attacks, there have been 33 recorded cases of shark bites -- including two resulting in death -- in Australia so far in 2018, according to the Australian Shark Attack File of the Taronga Conservation Society Australia.